IX. The Determination of Specific Nitrogen Compounds

Abstract

The determination of nitrogen in a biological sample usually involved the total nitrogen content, as in the case of proteins, mucopolysaccharides, or other compounds of biochemical interest, or the major portion of the nitrogen, which may occur in the form of α-amino nitrogen. However, it may occasionally be necessary to determine a quantity of a nitrogenous compound present in only a trace amount. It is under such conditions that a modern physical technique proves to be so valuable. In food analysis, it is very important to establish the quantity of N-nitrosamines in the cured meat or related product. Gough and Sugden⁴⁵ have developed a dual-column gas-chromatographic system for use in the mass-spectroscopic determinations of N-nitrosamines. They described an application of their system to the determinations of N-nitrosodi-methylamine and N-nitrosopycrolidine in cured meats and related products. Two stainless-steel columns are connected in series and operated at 140°C with helium (4 ml/min) as carrier gas. One column of dimensions 1.6 m × 1.8 mm is packed with 15% Carbowax® 20M on AW-DMCS Chromosorb W® (80 to 100 mesh), and the other column, of dimensions 30 m × 0.5 mm, is a support-coated open tubular column containing Carbowax 20M.